BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp
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.Dd November 25, 2014 .Dt GETIFADDRS 3 .Os .Sh NAME .Nm getifaddrs .Nd get interface addresses .Sh SYNOPSIS n ifaddrs.h .Ft int .Fn getifaddrs "struct ifaddrs **ifap" .Ft void .Fn freeifaddrs "struct ifaddrs *ifp" .Sh DESCRIPTION The .Fn getifaddrs function stores a reference to a linked list of the network interfaces on the local machine in the memory referenced by .Fa ifap . The list consists of .Nm ifaddrs structures, as defined in the include file n ifaddrs.h . The .Nm ifaddrs structure contains at least the following entries: d -literal struct ifaddrs *ifa_next; /* Pointer to next struct */ char *ifa_name; /* Interface name */ u_int ifa_flags; /* Interface flags */ struct sockaddr *ifa_addr; /* Interface address */ struct sockaddr *ifa_netmask; /* Interface netmask */ struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ struct sockaddr *ifa_dstaddr; /* P2P interface destination */ void *ifa_data; /* Address specific data */ .Ed
p The .Li ifa_next field contains a pointer to the next structure on the list. This field is .Dv NULL in last structure on the list.
p The .Li ifa_name field contains the interface name.
p The .Li ifa_flags field contains the interface flags, as set by .Xr ifconfig 8 utility.
p The .Li ifa_addr field references either the address of the interface or the link level address of the interface, if one exists, otherwise it is NULL. (The .Li sa_family field of the .Li ifa_addr field should be consulted to determine the format of the .Li ifa_addr address.)
p The .Li ifa_netmask field references the netmask associated with .Li ifa_addr , if one is set, otherwise it is NULL.
p The .Li ifa_broadaddr field, which should only be referenced for non-P2P interfaces, references the broadcast address associated with .Li ifa_addr , if one exists, otherwise it is NULL.
p The .Li ifa_dstaddr field references the destination address on a P2P interface, if one exists, otherwise it is NULL.
p The .Li ifa_data field references address family specific data in a pointer to the .Fa struct if_data (as defined in include file n net/if.h ) . For .Dv AF_LINK addresses, it contains various interface attributes and statistics. For all other address families, it contains per-address interface statistics.
p The data returned by .Fn getifaddrs is dynamically allocated and should be freed using .Fn freeifaddrs when no longer needed. .Sh RETURN VALUES .Rv -std getifaddrs .Sh ERRORS The .Fn getifaddrs may fail and set .Va errno for any of the errors specified for the library routines .Xr ioctl 2 , .Xr socket 2 , .Xr malloc 3 or .Xr sysctl 3 . .Sh SEE ALSO .Xr ioctl 2 , .Xr socket 2 , .Xr sysctl 3 , .Xr networking 4 , .Xr ifconfig 8 .Sh HISTORY The .Nm implementation first appeared in BSDi sx . .Sh BUGS If both n net/if.h and n ifaddrs.h are being included, n net/if.h .Em must be included before n ifaddrs.h .